Interlocking system for railroads



June 28, 1938. 'c. s. BUSHNELL 2,121,785

' INTERLOICKING SYSTEM FOR RAILROADS Filed April 8, 1936 2 Sheets-Sheet Y1 IIIQI i q ll N .8

flaw 16 ATTORNEY June- 28, 1938. c. s. BUSHNELL I INTERLOCKING SYSTEM FOR RAILROADS 2 Sheets-Sheet 2 Filed April 8, 1936 Q l f) ilhL V I route end'relay for each; end of each route, and to Also, if an operator has before him aminiature track layout corresponding to theactual track 7 lso'far as this entranceexit fmanipulationj is con-.

cerned, the present invention is an improvement over the systems .disclosed in the 'prior"applica-' tions of S. N. Wight Ser. No. 721,696 filed April Patented Jiuie 28, 1938 UNITED STATES P TE T forries 7 2,121,685 YIVNTERLOCKINVG FSYSTEM FoR ammons] 7 Charles S. Bushnell, Rochester, -N. Y., assignorw' to General Railway ter, N. Y.

Signal Company, Roches- Application April 3; 1936,'Serial o i'zasza f 19 Claims. (Cl. 246-434) g This invention relates to an interlocking system of the free lever type forrailroads, and more particularly to an interlocking system of the entrance-exit type in which a route is defined by operating a button at the'entranceto such route on a, miniature track layout and by operating another button at :the exit endof the route on such miniature track layout.

Since, in mostinterlocking systems, the num ber of routes that may be setupgreatly exceeds the number of entrance points tosuch routes, a considerable saving in manually operable devices and considerable simplification results ifa particular route is defined by designating its beginning and its end; and without giving any consideration to the track. switches involved therein;

21, 1934 and 20, 193.6."

More specifically, it is proposed in accordance with the present invention to employ'in con- I nection with the miniature track layout a polar Serial No. 69,905 filed ,Miarch preferably provide. a rotatable .entrance button which may be left inits operated position to pick up the polar relay toa particular polar position at, ,the entrance of the route to be selected, to pickup the polar :relay at the exit endv of'the route in thesamepolar direction by aip'ush exit buttonwhich will return" to its normal position when released, and'fto providea stick circuit for: this latter relay which will stick up througha' front'contact of the former relay onlyif the track switch control relays are in a position "to define the particular route defined by these relays." The polarity of energization'of 'these relays defines the direction of train travelwover such route. In

over may be considered as two switches.

addition it is proposed to provide a routecircuit to'clea'r a signal over such route only in the event that the track'switcheshave actually responded to set up the route defined .by the two energized route end relays. g i Another feature of-the' present invention resides inthe provision of a polar switch machine i r relay whic m y be. energized either through: circuits controlled by theflroute end relays defining the entrance and exit ends of aroute including thetrack switcher may be, controlled in case of emergency 'by'circuits'controlled by a switch machine lever, the organization of circuits being such that'if the switchmachine control relay is once energized it cannot be energized to a reversefpolar position'unless such relay is first allowed to assume the deenergized position. This ordination of the circuitsfconstitutes one of the interlocking features of; the present invention; ."jOther bbjects, purposes andch'aracteristic features of the invention will in part be pointed-out in'the specification hereinafter and will in part be obvious from the accompanying drawings, in Which:--

Fig." 1A shows conventionally the apparatus located in an office or tower; and Fig. 1B shows-the actual track layoutin the field and which corresponds to the miniatur'e track layout in the ofiice and-if Figs, 1A and lB ar-e laid end toend they show the selected embodimentof the 'invention as to the entire interlocking system, 1 f

f Apparatusin the field Letus'refer toFig." 1B in whichthere has been illustrated conventionally a rathersiinple form of interlocking track'layoutfwhich in practice may take a much more complicated form, and which comprises tracks land 2 connected by crossovers 6 and 'l to afiord four routes fromleft to right exclusiveof the run-around route over both cross-overs B and. I l'reversed, making a total numberof five. routes from left-to right and an often routes. 'It-is of courseunderstood that these routes may also include: switches which are not part of a, cross-over, and that each cross- The novel switch machine control relay and its 00- track sections I and 2' as well as the cross-overs 6 and I are insulated as shown by insulating joints 8, to permit the application of the usual track circuits, of which a track circuit containing track relay. Tl and'battery 9 and a track circuit additional five routes from right to left, or a total 4 containing track relay T2 and track battery I only have been illustrated.

At the entrance for each east-bound route starting on track 1 is shown a signal S for each eastbound route starting on track 2 a signal S for each west-bound route starting on track I a signal S and for each west-bound route starting on track 2 a signal 8*. 'The signal for continuing an east-bound route on the track I has been designated S As illustrated the crossovers 6 and 1 may be operated by switch machines, SMB and SM'I, respective-1y. these switch machines may be of any suitable construction they are preferably of a construction as shown in the prior patent to Howe No.

1,466,903 dated September 4, 1923. These switch machines preferably include point detector contacts which are closed only if the switch points are actually in a particular extreme position and locked, and although these switch point detectors may be of any suitable construction they are preferably of a construction as shown in the prior patent to Bushnell No. 1,517,236 dated November 5, 1924. These point detector contacts of switch machines SMB and SM! are connected to respectively control switch repeater relays WPS and WP'I, asa result of which these relays WP6 or WP! will beenergized to a particular polar position only if the corresponding switch machine assumes a corresponding extreme position and is locked. These switch machines SMfi and SM! are preferably controlled by switch machine control relays Z6 and Z1. The signals .8 S S and S are preferably manually controllable by signal control relays GI, G2, G3, and G4, and may be of any suitable construction. These'signals in addition, to

this manual control are preferably subject to automatic track circuit control, such as well understoodbythose skilled in the art of railway interlocking, and preferably indicate a clear position if its corresponding G relay is energized and two blocks in advance of the signal are unoccupied; indicate caution if the associated G relay is energized, the first block in advance is unoccupied but the second block in advance is occupied; and indicate a stop position if either the associated G relay is. deenergized or the block immediately in advance of the signal is occupied; all as shown in said prior application of S. N. Wight and as conventionally illustrated by dotted lines ll, l2, l3, and M respectively connecting the signals S S S and S to their respective G relays.

It is well understood by those skilled in the art of railway signalling and interlocking, that a power-operated switch machine should not be permitted to be operated when it is unsafe to move the switch points, and although a lock relay controlled in any of the various well known ways may be employed to prevent operation of the switch machines SMB' and/or SM'l, a simple form of electric locking means for the switch machines has been illustrated in the form of lock relay L. In the particular arrangement shown the lock relay L, which must be energized to allow operation of either the switch machines SMS or SM! and can be energized only if all of the signals S S S and S are at stop and the two detector track relays Ti and T2 are energized and reflect non-occupancy of the track sections l and 2. This control circuit for the relay L may be traced from the'terminal of a suitable battery, through back cont-act 2B of signal relay G3, back contact 2| of signal relay Although G4, back contact ,22 of signal relay G2, back contact 23 of signal "relay Gl, front contact 24 of track relay T2, and front contact 25 of track relay Tl, through the winding of relay L to the Apparatus in the ofitce In the tower or oflice is located a miniature trackflayout which corresponds in every respect to the. actual track layout in the field. At the entrance point to each route portion of the miniature track layout is located a suitable manually operated entrance button which is preferably of such construction that, if operated, it will remain in its operated position. These levers or buttons are preferably rotatable and have been designated E E E and E and are used for initiating the clearing of the signals S S S and S respectively, located on the actual track lay-. out. These buttons E etc., are preferably buttons of the rotary type which are turned to an angle of 90 degrees either to the right or to the.

left depending upon whether the signal they con.- trol defines trafiic to theright or to the left, and in the event that the butto-n may control one signal to the right or another signal to the left, as is true of the button E these arrows indicate the direction in which trafiic is to move over the actual track layout. In addition there is located at the exit end of each route an exit push button PB (with suitable exponent). This push button PB is to reflect the exit endo-f the route and as will be pointed out hereinafter need be depressed only momentarily to complete the selection of a particular route or portion of a route. These push buttons have been designated PB PB PB PB and PB". Each entrance button E ,etc., has associated with it a route relay RR etc., for each direction governed by such entrance button. The entrancebutton E1 since it governs traflic in two directions has two route end relays RR and RR associated therewith. As illustrated these route end relays have been designated RR RR BB RR, and EH and these relays BR BB etc. may be controlled by these entrance buttons-E etc. or by the associated pushbutton P13 etc., all in a manner as more specificallypointed out in the operation of the system hereinafter.

In the officeare provided switch machine control relays SMR and SMR" for controlling the field switch machine control relays Z5 and Z? respectively. Each of these relays SMR. and SIVIR has associated therewith a manually controllable energizing lever, such as levers SML and SML' These levers SML and SM L normally assume their middle inactive position, and when in such position allow the associated relay to be controlled by any one of a plurality of circuits, each circuit'of which includes the front contacts of two route end relays RR (havingexponents defining the ends of the route) in series. .These relays S MR. and SMH are electrically connected to their associated emergency levers and to the energizing circuits through frontcontacts of these route end relays so that if one of these relays SMR or SMR' is once energized it cannot be operated to a different polar position without first causing deenergization of the relay, and the structure is such that the emergency lever cannot break aroute end relay energized circuit which is in conflict with the then position of such lever. This'feature isemployed so that if a route has once been set up through the medium of the route-end relays, this route cannot be "disturbed by operation of the manually operable switch machine'lever, such as lever SML or S'ML", to a conflicting position. In addition to the tower apparatus already described there 'are' also provided route circuits for energizing the various signal relays GI, G2, G3, and G4 in the field, the nature and function of these circuits will be more specifically described in the operation of the system hereinafter. v i I j Operation 7 Let us assume'that the operatorwishes to clear an east-bound route extending from signal S to signal S In'order to do this .he will operate the energize the upperwinding of the relay RR through the following. circuit:beginning at the terminal of the ofiice battery, contact 63 of entrance button E assuming its left-hand position, upper winding of the relay RR and normally closed push button contact 33 of the push button PB 'I'he'current in this circuit will be of 'a polarity to operate the polar contact 21 to theright, and if it not already assumes the righthand position will operate it there and will pick up the neutral contacts 28 and 29. li'he operator will next depress the push button-P3 and in so doing will energize the upper winding of the relay RR through the followingv energizing circuitz-beg'innihg at the terminal of the ofiice battery, back contact 38 of the push button PB upper winding of the relay RR through normallyclcsed contact 43 of entrance button E to the other terminal This-current is of a polarity to operate the'polar contact 30 .of relay BB to the right-hand position, and unless it already assumes the right-hand position will so operate it, and will also close the front contacts 3| and 32 of this relay.

With the route end relays RR. and RR? energized, therelay SMRfiis energized toits normal energized position through the following circuit:beginning at the terminal of a battery, front contact '34 of the relay RR ,'front contact 35 of the relay RB normally closed contact 36 of the emergency lever' SML normal winding N of the relay SMIR back contact 31 of the relay SMR to the terminal Closure of this energizing circuit causes relay SMR to move its polar contacts to the right and to pick up and,

RRF, normally closed contact 4| of the emer gency lever SML' normal winding N of the relay SMR through back contact 42 of the relay SMR' to the other terminal of said battery. The closure of thiscircuit will cause the relay SMR to move its polarcontacts to the proper position and close its front neutral contacts and open its back neutral contacts; It may be pointed out here that therelays SMR and SMR are not called upon to pick up through their own back contacts, for each back contact has in multiple therewith a polar contact and since the, polar contacts of a polar-neutral relay operatev quicker sulting in deenergization of this relay BB than the neutral contacts the stickcircuit -is maintained through the polar contact before thepick-up circuit is broken. I With the neutral contacts 44 and '41 of the relays SMIR and. SMR' closed, and with the rclosedr-beginning at the terminal of the office battery, front contact 28 of the relay RR), polar contact .21 0f therelay RR to the right,

contacts 44 and 45 of the relay SMR contacts 46 and 41 of therelay SMR", contacts 30 and'32 of the relay BB through the lower winding of thisrela'y BB to the other terminal of the said. battery. It will be noted that the circuit just traced is a stick circuit for the" relayRR; because it includes the stick contact 32. operator may now release the push button P3 the relay RR remaining heldenergized through this stick circuit.

With the switch machine control relays SMlt and SMR. both energized with their polar contacts to the right, the switch control re Iays Z B and Z1 will be energized by current of a polarity to operate or maintain the switch machines and SM! in their normal position. Also, with the track switches 6 and I both assuming their nor mal position, and with their switch points locked, the switch repeater relays WP6 and WP! will be energized to reflect the normal condition of the cross-overs 6' and 1, namely, will be energized with their polar contacts to the right and with their neutral front contacts closed. With the relays RR WP6, WP'I, and RR ,all energized tothe right, the following circuit for energizing the signal relay GI is closed:-beginning at the terminal of a suitable battery, 'normally closed contact 5110f the push button P13 polar contact 5| and neutral contact 52 of the relay BB neu tral contact 53'and polar contact 54 of the relay WP'I, polar contact 55 and neutral contact '56 of the relay WP6, neutral contact 51 and polar contact 58 of the relay RR}, wire 59, winding of the relay Glfto the other terminal of the same source. With the relay G! energized and provid ing traflic conditions in advance of the sig nal'S are clear, the signal S will be clearedto permit traffic to move over the track section I from the signal S to the signal S After the train which is to move over the track section l has moved beyond the signal S the operator may returnthe entrance button E to its normal position'as'a fresult of which the relay RR will be deenergized and will by opening of its neutral contact 28 in-' terrupt the stick circuit for the relay RRire- Similarly, droppingof contacts .35 and 39 of there: liay RR will result in deenergization of the switch machine control relays SMR and SMRF, and similarly dropping of contacts 51 of relay RR will result in deenergization of the signal control-relay GI, thereby placing the signal S in its stop condition.

It is readily noted that if the operator desires to move trafiic from right to left over the same track section I, he will operate the entrance but ton E to the lefttthereby energizing the relay RR to the left. Similarly, he will next depress the push button PB resulting in energization' of the relay RB to the left, as a result of which the relay RR may be stuck up through its stick contact 29 through the same route reflecting con-- tacts 44, 45, 46, and 41, through the front contact 3| of the. relay RR The switch machine control relays SMR and SMR" will, of course, be again energized to the right for the same reasons 'as already explained, this because the same route relays are energized for the same route irrespective of Whether trafiic is tomove from right to left or from left to right. Since, however, the route end relays RB and BB are now energized to their left-hand position, the signal relay G3 is energized instead of the'signal relay GI. .This energizing circuit for the signal relay G3 may be traced as fo1loWs:--beginning at the terminal of the oilice battery, normally closed contact 6| of the push button PB polar contact 58 and neutral contact of the relay RR neutral contact 56 and polar contact 55 of the switch repeater relay WPB, polar contact 54 and neutral contact 53 of the switch repeater relay WP], neutral contact 52 and polar contact 5| of the route end relay BB wire 62, winding of the relay G3 to the other terminal of said battery. With the relay G3 energized the signal S will assume a'clear, caution or stop condition depending 'on traffic conditions in advance of such signal. Obviously, the return of the entrance button E to its normal position will result in deenergization 'of the route end relays RR, and RR and in turn will result in deenergization of the relay G3, and will place the signal S3 back in its stop condition. In the same manner as just explained in connection with track section I, traffic may be set up from leftto right or from right to left over the track section 2, andfor this reason like contacts associated with the apparatus of track section 2 have been assigned reference numbers that are higher by forty than the reference characters applied to corresponding devices of the route over track section I.

Let us now assume that the operator wishes to allow a train to move from a point to the rear of signal S on section E to a point to the right of signal S on the section 2. To set up this route the operator will turn the entrance button E to the right, thereby resulting in energization of the relay RB tothe right, for reasons already given. The operator will then depress the push button PB as a'result of which the relay RR will be energized through a circuit beginning at the terminal of a battery, through back contact 18, through the upper winding of relay RR, through the contact 83 of the entrance button E to the other terminal of the same battery, as a result of which the relay BB will be energized til the push button P3 is released.

With the route end relays RR, and RR now energized the switch machine relay SMR" will be energized negatively, that is, so as to operate its polar contacts to the left through the following energizing circuit:beginning at the terminal of the omce battery, front contact I05 of the route relay RR front contact I06 of the route end relay RR normally closed contact 'I M of the emergency switch machine lever SMU, the reverse winding R, of the relay SMR", through the back contact I08 of the relay SMRF, to the other terminal of said battery. The polar con, tact I09 of the relay SlVlIR, will operate more quickly than will the neutral contact I08, so that the energizing circuit Will be shifted from the contact I08 to the contact I09. With the relay SMR now energized to the left, and with the relay SMR now energized to the right through a circuit including front contact 14 of relay RR and front contact 35 of relay RR the following stick circuit for the route end relay RR is closed:beginning at the terminal of the *ofiice battery, front contact 28 of therelay RR polar contact 21 of the relay RRHneutral'contact V 44 and polar contact 45 of the relay SMRF, polar contact 86 to the left and neutral contact 81 of the relay SMRfl, polar contact III to the right and neutral stick contact 12 ofthe relay RR through the lower winding of this relay RRfi to the other terminal The relay Z! will of course follow relay SMR. and will cause the switch machine SM! and cross-over I to be reversed and'cause relay WP'I to be operated to the left. energized to the right, and with the relay WPI energized to the left the following energizing circuit for the signal relay GI is closed:,--beginning at the terminal, of the oflice battery, front contact 90 of the push button PB polar contact 9| to'the right and neutral contact 92 of the relay RR neutral contact 93 and polar contact 94 to the left of'the relay WP'I, polar contact 55 to the right and neutral contact 56 of the relay WPB, neutral contact 51 up and polar contact 58 to the right of relay RR wire 59, winding of the relay GI to the other terminal With the signal relay GI energized the signal With the relays BB BB and WPIS now S will assume the clear, caution or stop position 7 depending on traffic conditions in advance of signal S over the route just set up, namely, the

route starting on track section I, passing over will result in energization of the relay RR to the left. The operator will next depress the push button PB as a result of which the relay RR. will be energized to the left. With the route end relays RR and'RR energized the following energizing circuit for the relay SMR is closed:- beginning at the terminal of a battery, contact I20 of route end relay RR front contact I2I of route end relay RR through normally closed contact I22 of the emergency switch machine lever SML through the reverse winding R of the switch machine relaySMRfi, through the back contact I23 of the relay SMR to the other terminal Since the polar contact I24 will operate more quickly than will the neutral contact I23, the energizing circuit just traced will be shifted from'the back contact I23 to the left-hand polar contact I24 of the relay SMR thereby resultinginenergization of the relay SMR to the left. The relay SlVl'R" will, of course, be energized in its right-hand position through the following energizing circuit:-beginning at the terminal of a battery, contact I2! of the relay RR front contact I28 of the relay 3R normally 7 closed contact II of the emergency switch machine lever SML through the normal winding N of the relay SMR through the polar contact I09 assuming its right-hand position to the other terminal With the relay SMR' energized to the right the switch machine SM'I will, of course, operate the cross-over I back to its normal position. With, however, the relay SMR energized to the left the relay Z6 will be energized to the left thereby operating the switch machine SMS to its reverse position. As soon as the crossover 6 has assumed its full reverse locked position the switch machine repeater relay WPB will asthe switch machine repeater relay W'P'I energized tothe right, the following energizing circuit for the signal relayGS is closed:'-beginning at the terminal of the office battery, normally closed push button contact lill of the push buttonPB polar contact-98 to the left and neutral contact 91 .of the relay RR up, neutral contact 96 up and polar contact 95 of the switch repeater relay WP6 to the left, polar contact 54 to' the right and neutral contact 53 of the relay WP! up, neutral contact'52 up and polar contact 5| of therelay BB assume a clear, caution or'stop condition dependto the left, wire 62, winding of the relay G3. With the relay G3 now energized the signal S will ing upon traffic conditions in advance of this sig-' nal over theroute just set up,-namely, the'route starting at the signal S extending to the left'on tracksection I, over cross-overli-ontotracksection 2-to the left'of signal S This route: may after the train has passed thereover'be relinquished by the operator returning his entrance turn button E to its normal position.

In the same manner as just explained traffic may move in the opposite directions over the same trackroute, as for instance, from signal S over cross-over 6 to signal S or from signal S over cross-over l to signal S.

There is still another route from left-toright as well as from right to left which has not yet been mentioned, and which cannot be set up by the use of the turn buttons E E E or E in combination with push buttons PB PB P3 or PB alone. This route is what is termed as a runaround move and comprises aroute over the two cross-oversfi and I reversed in series, so to speak. That is, aroute extending from signal S to signal S over cross-overs 6 and l or extending from signal S to S over the same cross-overs. This route may be set up by the operator providing no route is then set up by moving his emergency switch machine levers 'SML and SML" to the raisedposition, as a result of which the switch machine-relays SMR and 'SMRF are both energizedto the left. 'Ifthe operator, with the levers SML and SML 'both in their raised positions and with relays SMR and SMR. to the left, operates the entrance turn button E to the right and'depresses the push button 1 3 the relay RR will be stuck up through the following stick circuit:-- beginning at the terminal of the office battery, front contact 68 of relay RR up, polar con-- tact 61 of this same relay to the right, neutral 7 contact 84 up' and polar contact 85'to the left of the relay SMR polar contact 86 to the left and neutral contact 81 up of the relay SMR", polar contact-l to the right and neutral contact 12 mini the route end relay BB through the lower winding of this route end relay BB to the other terminal With the relays RR, and BB now energized to the right and with the switch.

machine repeater relays WPG and WP! energized to the left, as a result of the operators manual manipulation'of levers SML and SML resulting in .energization of relays SMR and SMR" to the left, the following energizing circuit for the relay" G2 is closed:beginning at the normally closed push button contact SO-Of the push button P13 polar contact 9| and neutral contact 92-01" relay RR neutral contact 83 upand polar contact '94 to the left of relay WPI, polar contact 95"to the left and neutral contact 96 up of the relay WPB,

front contact 91 and polarcontact 9 8 tothe right of the relay RR, wire.99, windingv of the relay G2 to the other terminal With this energizing circuit for thesignal control relay G2 closed, the signal S may assume the clear, caution orstop condition depending on traffic conditions in ad- I vance of the signal S over the run-around track route passing over cross-overs 6 and l and to the right of the signal 8*. This run-around route will obviously not-be set up as a general rule, but

S both'of these signals S and S maybe con-[ trolled by the same entrance turn button E. This is indicated by the provision of anadditional route end relay. BB which may be controlled througha contact I30 of the turnlbutton E or a contact l3l' of the push button PB located to the right of the entrance button E in the same way as the. push-button P3 is located to the left. In this double use of the entrance button E the contacts are shown differently than is the case with entrance vbuttonsE E and E where only one signal is shown controlled by the same entrance button. More specifically, the contacts of the entrance turn button E are so constructed that thecontact 43 is connected to the negative terminal of the ofiice battery when the turn button is in its normal, its extreme right-hand or any position intermediate thereof, and is con-' nected to the positive terminal of this battery when the turn button E assumes the extreme left hand position. Similarly, the contact-I30 of entrance turnbutton' E3 is connected to the terminal when this button assumes either the normal, the extreme left-hand or any position intermediate thereof,but is connected to the positive terminal of this battery'whenthe turn button E assumes the extreme right-hand posigized, the polar contacts being to the right and the neutral contacts being up, and that the operator lifts the lever SML and moves the contact I22 :into' engagement with its stationary contact connected tothe terminal of the office battery; The closure of 'the reverse circuit at this point will be of no avail, because this circuit is open at the left-hand polar contact I24 and is also opened at the 'backcontact I23 of this samev relay SMR In other words, the switch machine control levers SML and SML" are only available tothe operator to control the relays SMR or SMR" when these relays have notalrea'dy been.

energized by theroute control route end relays 3R 3R R13 or RR Attention is directed to the fact that the control circuit for the switch machine SMG passes through front contact I35 of the lock relay L and through contacts I36 and l3'lof relay Z6. Also, thatthe switch control circuit for the switch machine SM! passes through front contact 138 of lock relay L and contacts I40 and MI of relay Z1. From this it is apparent that the switch machineSMS and SM? cannot be operated unless the relay L is energized. It should also be noted that the lock relay L is energized only if all of the signal relays GI, G2, G3, and G4 are deenergized and then only if the track circuits containing track relays TI and T2 are unoccupied.

Since switch machine control relays SMR and SMR, are so constructed that if one of their energizing windings N orR is energized the other one winding cannot be energized, a certain feature of interlocking is provided which is highly desirable. For instance, let us assume that a route has already been set up starting at the signal S and terminating at the signal S namely, with the relay SMR energized to the rightand with the relay SMR" energized to the left, andlet us further assume that the operator attempts to set up traffic in conflict therewith from signal S to signal S The operation of the entrance button E to the leftand the depression of the push button PB although this operation will result in energization of the relays RR, and RR will not result in a new route. "This is true because even though contact 19 of relay RR. and contact 46 of relay RR. are closed and do connect the positive terminal of the office battery to the upper winding N of the relay SMR, this relay SMR' will not be operated because its polar contact I09 is to the left breaking one of the paths through winding N and the neutral contact -12 is in its raised position thereby breaking the other partial circuit for the normal winding N, so that the relay SMR is not operated. Obviously, if the relay SMR" cannot be operated to set up the second route the switch repeater relay WP cannot be operated and the route circuit for such second route cannot be closed at the contacts of the switch repeater relay WPT. What has been said about the normal circuit for relay SMRfl-including contacts 19 and 40 of relays RR and BB is also true of the reverse circuit for relay SMR' including contacts I20 and I2! of these same relays RR and BB so that both of relays SMR, and SMR remain energized as they were and the route from signal S to Signal S will not be disturbed. The feature that the relays SMR and SMR cannot be energized to a different polar position when once energized, unless the energizing circuit is first broken, constitutes one of the principal interlocking features in this system in preventing a second conflicting route from being set up. This is true because a conflicting route invariably involves the operation of switch points to a different position. This same interlocking feature, however, permits parallel routes involving the same cross-overs to be set up, this is true because for setting up routes in parallel the cross-overs will assume the same position for both routes. In other words, applicants interlocking feature, which to a certain extent resides in the peculiar and novel circuits for controlling the switch machine relays, affords interlocking against the actual changing of a route, but permits parallel routeson adjacent tracks and having cross-overs in common therewith to be set up.

The applicant has thus provided a route relay which defines each end of each track route portion, and he has provided a'route circuit for sticking up one of these route relays through a front contact of the other route relay so that only momentary operation of the push button,

whichd'efines the exit point of the route, is necessary. He has provided a plurality of circuits in multiple for operating switch and cross-over points, the circuit organization being such that the first control circuit. for such switch machine relay closed is the dominating one and. the subsequent closure of other control circuits at the control point therefor are of no avail, and he has further provided signal'selecting route circuits which can be closed only if two route end relays defining a particular route are energized and providing all of the switches contained in such route assume a position to define such route. In addition to this construction the applicants system is such that the operator need not take into consideration the number of switches in a route to be set up, nor the position which they assume, for all that the operator is called upon to do is to operate an entrance turn button at the entrance end of the route he desires to set up and to momentarily depress an exit push button at the exit. end of such route. Attention is also particularly directed to the normally closed push button contacts 50, 6|, 9%, and llll included in the various route signal, circuits forrelays GI, G2, G3, and G4. These normally closed push button contacts areprovided to require the operator to return his exit push button to its normal position before the signal governing trafiic over the route in question can actually assume its proceed condition.

It is to be understood that certain features of the system may be dispensed with. For instance, if the push buttons non-spring returned the route circuit for sticking up one route relay through a front contact of the other might be dispensed with. Also, if desired, the emergency levers may be omitted, and the push button contacts in the signal relay circuits may be omitted. Also, any suitable approach and release locking such, for instance, as shown in said prior appli- 'cation"of S. N. Wight may be used, if desired.

Also, instead of employing route end relays, as shown, manually operable contacts may be used in place thereof in which case the contacts will be three-position and not polar and neutral. The double throw contacts operated directly by the levers SlVlL and SML" are preferably constructed make-before-break, so that an energized coil of the associated relay cannot be deenergized, and if desired the normally closed contacts thereof may be entirely dispensed with, in which event the control circuits extending from route end relay contacts are connected directly to the proper winding of the associated relay.

Having thus shown and described one rather specific embodiment of the invention and having shown this embodiment of the invention applied to a rather simple interlocking system, it is desired to be understood that the particular em- 7 bodiment, as well as the simple interlocking systemto which it has been shown applied, have been selected merely to afford description of the invention and its underlying principles, rather than give the scope thereof; and that various changes,

modifications, omissions and additions may be made in accordance with well known signal practice to adapt the invention to other track layout, other types of signals, control buttons or the like, all without departing from the spirit or scope of the invention or the idea of means underlying the same, except as demanded by the scope of the following claims.

I What I claim as new is:

1. In an entrance-exit type interlocking systom, the combination with a track layout having a plurality of routes over portions of track between'signals governing'train movement in the same direction, each of said routes including one c or more switches and many of which have entrance or exit points at signal locations in commom, a route end relay for each signal location, a switch machine for'each of said switches, a

7 switchmachine control relay for each switch 1' machine, manually operable means for controlling said route end relays, circuits for controlling said switch 'machine'control relays by said route end relays, each of saidswitch control'relays having energizing circuitsl separate from those for ener gizing other switch control relays, each of said energizing circuits for each switch control relay belonging individually to one of the routes over the corresponding switch and including contacts of the route end relays for the o'pposite'ends of I such route, and asignal control circuit for each route including contacts reflecting the positions assumed by the switches therein and contacts of'the route endrelays atthe entrance and exit ends thereof. Y t

2. In an entrance-exit type interlocking system, the combination with a track layout having a plurality of routes over portions of track be tween signals governing train movement in the samedirection, each of said routesincludingtwo or more switches or cross-overs and many of gizing'said switch machine relays of said switch machines in multiple by; said route end relays, ea'ch circuit including contacts oftwo route end relays, and'a signal control circuit for each route including contacts reflecting the positions as-' sumed by the switches and/or cross-overs therein and'contacts of the route'end relays at the entrance and exit ends'thereof. r v

3. In aninterlocking system, the combination with a track layout having a plurality of routes each including one or more switches and many routes/of which have entrance or exitpoints in common, a signal for each entrance point, a polar route endrelay for each point, switch machines for controlling said switches, a switch machine control relay for each switch machine, control circuits for said switch machine control relays each including contacts of two route end relays,

two manually operable means at each point one for energizing the associated route end relay to a polar position to govern'traffic into a route at that point and the other to' energize such route end relay to a polar position to'govern traffic out of a route at that point, and a signal control circuit for each route including contacts reflect' ingthe positions bf switches in such'route, the, I contacts of a route end relay energized to an entrance position and the contacts of a route end relay energized to any exit position.

'4. In an interlocking system-,the combination with a track layout having a plurality of routes each including one or more switches and many routes of which have entrance or exit points in common, a signal for each entrance point, a polar route end relay for each point, switch machines for controlling said switches-a switch machine control relay for each switch machine, control- I circuits" for said switch machine control relays each including contacts of two route end relays, two manually operable means at eachpoint one for energizing the associated route end relay to a polar position to govern traffic into a route at that point and the other to energize such route end relay to a polar position to govern trafilc out of a route at that point, and a signal control circuit ,for controlling the signal at the entrance of such routeincluding contacts reflecting the positions of switches in such route, the contacts of'a route end relay at the entrance end of such route energized to an entrance polar position and the contacts of a route end relay at the exit end of such route-energized to an exit polar position. 7 a

' 5.-In an interlocking system, the combination with a track layout having a plurality of routes 7 each including one or more switches and many routes of which have entrance or exit points in common, a signal for each entrance point, switch machinesfor controlling. said switches, a-polar route'end relay for each point, a normal circuit for each switch machine including in series the front contacts of two route end relays defining a route including the track switch con trolled by such switch machine in its normal position, a reverse circuit for each switch machine including in series the front contacts of two route end relays defining a route including thetrack switch controlled by such swit'ch'ma chine in its reverseposition, manually operable means for-controlling said polar route end relays-and a'signal control circuit for'governing the signalat the entrance of a particular-route including contacts reflecting the polar energized conditions of the polar route end relay at the entrance and exit, end of such route and'cont-acts reflecting the positions assumed by track switches in such route.

6. In an interlocking system, the combination with a track layout having a plurality of routes each'including one or more switches and many routes of which have entrance or exit points in common, a signal for each entrance point, switch machines for controlling said switches, a polarrouteend relay for each point, a normal circuit foreach switch machine including in series the its reverse position, a manually controlled en P V trancebutton and a manually controlled "exit a button for each point; a circuit for each'route end relay to' energize it to an entrance polar position including a contact of the associated entrance button; a circuit for each route end relay to energize it'to an exit polar position includ ing'a' contact of the associated exit button; a

stick circuit for each'route end relay closed only if such route end relay is energized to its exit polar position and then only if another route end relay is energized. to an entrance 'polarposition; and

a signal control circuit for governing the signal at the entrance of aparticular route including contacts closed when the entrance route end relay for such route is energized to the entrancepolar position, including contacts closed when the exit route end relay is energized to the exit polar position and contacts reflecting themestio-ns assumed-by track'switches in such route;

.7. In an interlocking system, the combination with a track layout having a plurality of routes each including one or more switches and many routes of which have entrance or exit points in common, a signal for each entrance point, switch machines for controlling said switches, a polar route end relay for each point, a control relay for each switch machine; a normal circuit for each control relay including in series the front contacts of two route end relays defining a route including the track switch controlled by that control relay, a manually controllable entrance button and a manually controllable exit button for each point; a circuit for each routeend relay to. energize it to an entrance polar position including a contact of the associated entrance button; a circuit for each route end relay to energize it to an exit polar position including a contact of the associated exit button; a stick circuit for each route end relay including its own contacts closed only if such relay assumes the exit polar energized position, contacts of the entrance route end relay closed only if such entrance route end relay is energized to the entrance polar position and contacts of the control relays governing the switches in such route assuming a position to set up such route; and a circuit for controlling the signal at the entrance end of such route governing the movement of trafiic into such route including contacts closed only if the switches in such route assume a position to set up such route and the route end relays defining the ends of such route assumerespectively the entrance polar and the exit polar positions.

8. In combination, a polar neutral relay having polar contacts and neutral contacts, a normal winding for operating the polar contacts to the normal position and for picking up the neutral contacts, a reverse winding for operating the polar contacts to the reverse position and-for picking up the neutral contacts, a circuit for said normal winding including in multiple a back neutral contact and a normal polar contact of said relay, and a circuit for said reverse winding including in multiple a back neutral contact and a reverse polar contact, whereby said normal circuit cannot be closed if said relay is energized reverse and said reverse circuit cannot be closed if said relay is energized to its normal position.

9. In combination, a polar neutral relay having polar contacts and neutral contacts, a normal winding for operating the polar contacts to the normal position and for picking up the neutral contacts, a reverse winding for operating the polar contacts to the reverse position and for picking up the neutral contacts, a circuit for said normal winding including in multiple a back neutral contact and a normal polar contact of said relay, a circuit for said reverse winding including in multiple a back neutral contact and a reverse polar contact, a plurality of contacts for applying energy to said normal circuit, and a plurality'of contacts for applying energy to said reverse circuit, whereby said normal circuit cannot be closed if said relayis energized reverse and said reverse circuit cannot be closed if said relay is energized to its normal position. a 10. In an interlocking system, the combination with a track layout having a plurality of routes each including two or more track switches and many routes of which have entrance or exit points in common, a signal for each entrance point, switch machines for controlling said switches, manually controllable contacts for each of said entrance and exit points, a normal control circuit for controlling each switch machine including in series a. manually controlled contact for the entrance point and a manually controlled contact for the exit point of each route including the track switch controlled by said switch machine in the normal position, a reverse control circuit for controlling each switch machine including in series a manually controlled contact for the entrance point and a manually controlled contact for the exit point of each route including the track switch controlled by said switch machine assuming its reverse position, said normal and reverse control circuits for each switch machine being separate from and energized independently of the circuits for other switch machines, and a circuit for clearing the signal governing the entrance of traffic into such route effective when the manually controlled contacts for the entrance and exit points of such route are operated and contacts reflecting the positions of the track switches in such route reflect that such route is set up.

11. In an interlocking system, a track layout having a plurality of routes formed by one or more track switches and certain of such routes having entrance or exit points in common, manually operable means for each route end, relay means for each route end, circuit means for each said relay means controlled only by said man ually controlled means for that route end for at any time initially energizing that said relay means, switch control relays'for the track switches selectively and jointly energized in multiple by those of said relay means at the ends of routes including such track switches for setting up such routes,- and stick circuit means for each said relay means closed, when such relay means is energized for the exit end of a route and energized dependent upon said energized switch control relays for that route and dependent upon the condition of said relay means at the entrance end of such route.

.. 12. In combination, a polar-neutral relay having polar and neutral contacts, a first control circuit for said relay including in multiple a back contact of said relay and a polar contact of said relay in one position, a second control circuit for said relay including in multiple a back contact of said relay and a polar contact of said relay in the opposite position, and means for at times energizing said first or said second control circuits, said energization of said first circuit causing magnetic flux of one polarity and said energization of said second circuit causing magnetic flux of the opposite polarity in said relay, whereby said polar contacts are actuated to opposite positions depending upon which of said control circuits is energized.

13. In combination, a polar-neutral relay having two windings differentially connected and having polar and neutral contacts, said polar.

contacts moving to one position when one winding is energized and moving to the other position when the other winding is energized, a source of potential, circuit means for connecting one terminal of said one winding to one terminal of said source through a back contact of said relay in multiple with a polar contact of said relay in said one position, circuit means connecting one terminal of said other winding to said'one terminal of said source through a back contact of said relay in multiple with'a polar contact of said relay in said other position, and

- effective to operate said track switches to'set up:

means for selectively connecting the other terminals of said windings to the other terminal of said, source, whereby the first of said windings to..be energized causes the polar contacts of said relay tolbe operated to corresponding positions and the picking up of the neutral contacts and thereafter prevents the energization of the 0p-' posite winding. I

l4. lnganiinterlocking system, a track layout having a plurality of routes formed by one or more track switches and particular ones of such routes having common entrance or exit points,

ing said relays and said manually operable contact means for selectively energizing said switch control relay means initially for a particular route upon the actuation of said manually operable contact means for the opposite ends of that route whereby that route is set up through the track layout, and a stick circuit for each said relay at the exit end of a particular route set up selectively made up by said switch control relay means then selectively energized and dependent upon said manually operable contact means at the entrance end of that particular route.

15. In an interlocking system, a track layout having a plurality of routes formed by one or more track switches and particular ones of such routes having common entrance or exit points,

' I end, switch control relay means for each of said track switches for operating the corresponding track switch to normal or reverse positions when selectively energized, a relay for each route end, a pick up circuit for each said relay controlled only by said manually operable contact means for the corresponding route end, means including said relays and said manually operable contact means for selectively energizing saidjswitch control relay means initially for a particular route upon the actuation of said manually operable contact means for the opposite ends of that route whereby that route is set up through the track layout, a stick circuit for each exit relay at the exit end of a particular route set up selectively made up by said switch control relay'means then selectively energized and dependent upon said manually operable contact means at the entrance end of that particular route, and circuit means for clearing the signal at the entrance to a route set up only when the exit relay at theexit of that route is picked up. j

16. In a system for governing the operation of track switches and signals of a railway track layout, a portion of track having an entering signal governing traffic over a main route including said track portion and over other routes set up by track switches included in said track portion,

' ed with the exit end of said main route, an exit relay associated with said exit button, a pick up circuit for said exit relay directly closed by said exit button, route, establishing means rendered said main route and to clear saidentering signal inresponse to the operation of only said entrance button and said exit button and said means remaining effective only so long as said exit relay is maintained energized, and stick circuit means for said exit relayiclosed only after the of said route establishing means.

1'7. In an interlocking. system-of theentrance em't type, a track layout having a plurality or response;

routes formed by power operated track switches,

a control machine having a control panel, manually operable controlmeans on said panel for the opposite ends of the routes of said track'layout, relay means for eachof said manually operable control means and energized at any time in response to theactuation of its control means,

switch control means for said power operatedstick circuit means for each of saidrelay means.

efiective to maintain such relay means energized,

when it is energized for the exit end of a route,-

dependent upon said relay means for the entrance end of such route, said stick circuit means becoming efiective only after said switch control means for each of the trac'kswitches in that route have responded. l r

18. In an interlocking system for railroads of the entrance-exit type, a track layout having a plurality of routes each of said routes including one or more track switcheswith signals for governing traffic into said routes, a manually operablecontact ineansfor the opposite ends of said routes, route end relay means for the opposite ends of saidroutes and each being directly controlled by said manually operable contact means for its route end so as to be responsive to such contact means at any time, switch control means for each of the track switches and each controlled by the route end relay means forthe opposite ends of the routes in which the associated track switch is included in such a manner that the ac-f tuation'of the route end .relay means for the opposite ends of a particular route operates such track switch to a proper position for that particular route and thereafter prevents the operation of such track switchto a different position upon theoperation of a route end relay means for any ofthe other routes in which such route may be included, circuit means for maintaining energized the route end relay means for the exit end of a route dependent upon the route relay means such route actually have established that route.

19. In a system for governing the operation of track switches and signals; a portion of track having an entering signal governing traffic over a main route including said track portion and over other routes set up by track switches in cluded in said track portion; a manually operable entrance button for said entering signal; a selfrestoring exit button for the exit end of said main route; an exit relay associated with said exit button; a pick up circuit for said exit relay directly closed by said exit button; switch control relays for the several track switches governing the normal and reverse operation of said track switches; circuit means including-contacts of said exit relay for selectively energizing said switch control relays for the several track switches in multiple to cause the operation of the track switches to set up said main route, said circuit means being rendered effective in response to the operation of only said entrance button and said exit button and remaining eifectiveonly so long as said exit relay is maintained energized; stick CHARLES s. BUSHNELL. 

